A simple script to run asynchronous tasks sequentially. Alternative to async.waterfall

README.md

0tis-waterfall

A simple script to run asynchronous tasks sequentially. Alternative to async.waterfall

Install

npm i -S gist:81cb708f0ef01ed2d3ecf6e6aae43013

How to use

import waterfallTasks from '0tis-waterfall';
waterfallTasks([
  cb=>{
    const error = null;
    const data1 = 'good';
    const data2 = 'day';
    cb(error, data1, data2);//the first parameter is always an error, the other parameters will be passed to the next task.
  },
  (cb, data1, data2)=>{
    cb();
  }
], (err, data)=>{
  //do finally task
});

package.json

{
  "version": "0.1.0",
  "name": "0tis-waterfall",
  "main": "waterfallTasks.mjs"
}

waterfallTasks.mjs

async function waterfallTasks(tasks, callback){
  if(!Array.isArray(tasks)) {
    console.error('First argument must be an array');
    return;
  }

  let result = [];
  let err = null;
  for(let task of tasks){
    if(typeof task !== 'function') {
      console.error(`task is not a function: ${task}\nwaterfall continues to run`);
      continue;
    }

    [...result] = await new Promise(resolve=>{
      try{
        task((...array)=>{
          resolve([...array])
        }, ...result);
      }catch(e){
        resolve([e]);
      }
    });

    err = result.splice(0, 1)[0];
    if(err){
      console.error(err);
      break;
    }
  }

  if(typeof callback === 'function') callback(err, result);
}
export default waterfallTasks;